The optical response of biased nanostructure semiconductors with a
THz field are studied by calculating absorption spectra based on
semiconductor Bloch equations. We investigate dependence of
absorption spectra on the relative phase between optical pu...
The optical response of biased nanostructure semiconductors with a
THz field are studied by calculating absorption spectra based on
semiconductor Bloch equations. We investigate dependence of
absorption spectra on the relative phase between optical pulses
and THz field and continuous wave optical properties using short
pulse technique. All of the absorption spectra have Stark ladder
structures with energy spacing, $m\hbar \omega_B+m'\hbar
\omega_L$. There are actually frequency range where there is gain
for various phases. But, there is no gain region in the continuous
wave absorption spectrum. The optical gain without population
inversion results from the nonlinear sum and difference mixing of
the optical and the THz frequencies via the phases.